The chemokine, stromal derived factor-1 (SDF1) has been shown to modulate the homing of stem cells to its site by mediating chemotaxis. We demontrated overexpression of SDF-1 induced mobilization of cells with stem cell potential (CFU-S, long-term reconstituting cells). Moreover, SDF-1 activated matrix metalloproteinase-9 induced in bone marrow (BM) cells, causing the release soluble Kit-ligand and permitting the transfer of hematopoietic stem cells (HSCs) from a quiescent to a proliferative niche. The role of SDF-1 in the process of HSC migration and the mechanism underlying this HSCs migration will be reviewed. These studies lay the foundation for using SDF-1 to induce mobilization of progenitor cells in a BM transplantation setting.